Addressing a major transfusion safety issue, as of March 2004, AABB statute 5.1.5.1 mandates testing of all platelet units for bacterial contamination. The only commercially available tests for this purpose in the U.S. are culture-based tests which require 48-72 hours to deliver a result. Such tests are useful only for apheresis platelet testing, but not for random donor platelets. Under prior Phase I and Phase II SBIR grants, applicants developed a 50-minute test for bacterial contamination of platelets capable of detecting both gram-positive and gram-negative species at concentrations down to 103 CFU/ml. The test has been converted into kit form. Its simple procedure and pre-measured single dose reagents are aimed at the needs of transfusion services and blood banks which constitute the principal market. Compared with culture tests performed in the blood bank at the time of platelet collection, from which results must be extrapolated at later times, the proposed test is intended for application to platelet units at the point of release. Current point-of-release test methods rely on pH or glucose reagent strips, which have been shown to be inaccurate and insensitive. This new, fast and accurate test will increase the safety of transfused platelets and reduce the risk of transfusion-associated sepsis due to bacterial contamination, the number one cause of morbidity and mortality in transfusions today. It is the first test of its kind which can be applied to both apheresis and random donor platelet units. The BacTxTM test is based on the detection of peptidoglycan as a universal component of bacterial cell walls in both gram-positive and gram-negative species. The principle technological innovations underlying the BacTxTM test include (1) the application of an ultrasensitive enzymatic detection chemistry which is triggered by peptidoglycan, (2) the development of a sensitive colorimetric indicator to facilitate visualization and measurement of assay results, and (3) means for capturing bacteria from platelet concentrates for detection while avoiding interference and inhibition from platelets or other blood components. The main purpose of this project is to carry out a clinical trial of the diagnostic test kit developed under the previous Phase II program, to be submitted for FDA approval. As a device intended for screening blood products used in transfusion, this kit requires clearance by the FDA Center for Biologics Evaluation and Research (CBER) before it can be marketed with clinical claims as an in vitro diagnostic device. The clinical trial design will validate the sensitivity of the test in detecting bacteria spiked at various levels into platelet units, the specificity of the test in control units, and its reproducibility and stability. Its performance will be compared against culture as gold standard.